Loop taker drive mechanism for sewing machines

ABSTRACT

A drive mechanism for a pair of loop takers each cooperating with a separate needle of a two-needle sewing machine in which a single timing belt is used to drive both loop takers. An arrangement is disclosed which permits the spacing between the loop takers to be changed without disturbing the driving connections, and which provides for regulation of a single one of the connections in the loop taker drive with respect to the needle drive in order to reestablish proper timing of both of the loop takers with respect to the respective needle reciprocation when the spacing between loop takers is changed.

United States Patent Inventor Reinhold Papaiewski Buchig, Germany Appl. No. 43,061

Filed June 3, 1970 Patented Aug. 31, 1971 Assignee The Singer Company New York, N.Y.

LOOP TAKER DRIVE MECHANISM F OR SEWING MACHINES 3 Claims,5 Drawing Figs.

U.S. Cl 112/167, 112/184, 112/220 Int. Cl D051) 1/08 FieldoiSearch 112/184, 181, 189,191,202,163,l64, 167,228,220

References Cited UNITED STATES PATENTS 1,394,118 10/1921 Ringe 112/167 2/1926 Sharaf I Primary 'ExaminerH. Hampton Hunter Auorneys-Mzirshall .l. Breen, Chester A. Williams, Jr. and

Robert E..Smith ABSTRACT: A drive mechanism for a pair of loop takers each cooperating with a separate needle of a two-needle sewing machine in which a single timing belt is used to drive both loop takers. An arrangement is disclosed which permits the spacing between the loop takers to be changed without disturbing the driving connections, and which provides for regulation of a single one of the connections in the loop taker drive with respectto the needle drive in order to reestablish proper timing of both of the loop takers with respect to the respective needle reciprocation when the spacing between loop takers is changed.

PATENTED was 1am sum 1,v as 2 INVENTOR. Reinhold Popajewskn WITAESS:

I Y Z'TORNEY PATENTED AUG3] um SHEEI 2 OF 2 INVENTOR. Reinhold; Popo ewskl WITNESS;

film/I2 MOM LOOP TAKER DRIVE MECHANISM FGR SEWING MACHINES BACKGROUND or THE INVENTION the change of spacing becomes a tedious and timeconsuming operation.v

It is an object of the present invention to provide a novel drive for a pair of rotary loop takers in which the spacing or gauge between the loop takers may be changed without disrupting the drive, and in which after a change of loop taker spacing both loop takers may be brought into proper timed relation to their respective needles by effecting a single adjustment of the drive mechanism.

BRIEF SUMMARY OF THE INVENTION The above and additional objects and advantages of this invention are attained by a rotary loop taker for a pair of loop takers comprising a single timing belt interconnecting a driving sprocket with driven sprockets associated one with each of the loop takers. Idler pulleys are provided for directing separate loops of the belt one to each of the driven sprockets with each of'the belt loops having, identical angle of wrap and identical direction of belt travel relatively to the driven sprockets. As a result, when the loop takers are adjusted relatively to a common center line of seam formation to accommodate a different needle spacing, each loop taker will be shifted a like amount out of proper timed relation with its respective needle. By a single adjustment of the driving sprocket relatively to the sewing machine drive mechanism, therefore, both loop takers may be simultaneously brought into proper timed relation with the needles.

With the above object and the additional advantages of quietness of operation, freedom from adverse affect of abrasive foreign particles in the drive, and the ease of accommodation of wide tolerances of the parts, this invention is illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a vertical cross-sectional view of the bed portion of a sewing machine having two needles, two loop takers cooperating therewith, and having the loop taker drive of this invention applied thereto,

FIG. 2 represents an enlarged cross-sectional view taken substantially along line 22 of FIG. 1, showing one of the loop taker supporting saddle arrangements,

FIG. 3 is an enlarged cross-sectional view taken substantially along line 3-3 of FIG. 1 showing the slip clutch arrangement supporting the driving sprocket of the loop taker driving belt,

FIG. 4 is a bottom plan view of the sewing machine of FIG. 1 and FIG. 5 is a pair of diagrammatic representations of the belt drive for the loop takers of this invention showing the driven sprockets adjusted into the minimum and maximum spacing.

Referring to FIGS. 1 and '4, a sewing machine is illustrated having a bed 11, a standard 12 rising from the bed and sustaining a bracket arm 13 which overhangs the bed. The sewing machine is adapted simultaneously to form two separate rows of stitches, and to do this it is provided in the sewing head with a needle bar 14 to which is secured a needle clamp 15 which accommodates a pair of laterally spaced needles 16. A throat plate 17 carried on the bed to support work fabrics against the thrust of the needles is formed with apertures 18 through which the needles reciprocate endwise in the formation of stitches.

I Indicated generally at V 20 are rotary loop takersifor cooperating one with each of the needles 16 in the formation of stitches. Each loop taker is carried in a saddle indicated generallyat 21 which is shifiably supported lengthwise of the bed and may be clamped in selected position thereon. When'a different spacing between the separate lines of stitches. is required, a differentneedle clamp 15 is substituted having the desired gauge or needle spacing, a different throat plate substituted having the appropriately spaced'needle apertures and the loop taker saddles 21 must be shifted into anew spacing of the loop takers for cooperation with the changed needle gauge. As is conventional in this type of two-needle sewing .machine, regardless of the needle spacing, the needles will always-be arranged equally on opposite sides of a fixed medial plane. When needle gauge is changed, therefore, a shiftof the loop taker position of the two loop takers will always be required an equal amount in opposite directions.

The two loop taker saddles may be identical in construction, and identical in means of support, and therefore the same parts will be indicated by like reference characters in the drawings save that the parts of the right-hand saddle in the drawings will be denoted by prime numbers.

As best shown in FIG. 2, each of the loop taker saddles 21 comprises a closed compartment 22 through which a pair of vertical shafts 23 and 24 are joumaled. Meshing gears 25 and 26 on the shafts 23 and 24 respectively, are arranged within the compartment 22 and the loop taker 20 is secured as by a set screw 27 to one of the shafts 23 above the saddle'while a sprocket wheel 28 is secured to the other shaft 24 beneath the saddle.

Means are provided for shifting and for selectively securing each .of the saddles in any one of a range of positions lengthwise of the bed. Preferably to this end, each of the saddles is formed with parallel guide channels 30, one channel at each side of the saddle. As shown in FIG. 4, the sewing machine bed 11 is formed with spaced depending webs 31 and 32 extending lengthwise of the bed and between which the loop taker saddles are arranged. Securedby fastening screws 33 to the webs 31 and 32 are elongate ways 34 each formed with a guide surface 35 complemental to the guide channels 30 formed in the loop'taker saddles. The parts are so dimensioned that the ways 34 provide for a snug support for the loop taker saddles which nonetheless will accommodate a free slid ing movement of the saddles along the ways lengthwise of the sewing machine bed. At least one of each pair of the ways for each of the saddlesis formed with a recess 36 on the side opposite the guide surface 35 and between the fastening screws 33 so that the ways which are so recessed will have an unsupported central portion between the fastening screws. The web 31 is formed with a threaded opening which accommodates a screw 37 disposed to abut the way along the recess 36. A lock nut 38 is provided on the screw 37. By tightening the screw 37 the recessed way may be deflected so as to lock the hook saddle in a selected position along the ways. While each of the ways 34 may be formed with a recess 36 and provided with an adjusting screw 37, it has been found adequate to provide for deflection of only one of each set of the ways for each saddle in order to securely clamp the saddles in place on the bed.

As shown in FIGS. 1 and 4, a main drive shaft 40 is journaled in the bed beneath the standard 12 and provided with a pulley 41 by which the sewing machine may be powered from anysuitable motor, power transmitter, or the like. A suitable drive may be provided from the main drive shaft 40 to reciprocate the needles l6 and a timing belt 42 is illustrated in FIGS. 1 and 4 meshing with a sprocket 43 on the main drive shaft 40 for this purpose. The main shaft 40 may also have fast thereon rotary actuators 44 and 45 for imparting movement to a work feeding mechanism. As shown in FIG. 4, such a work feeding mechanism may include a feed bar 46 of a drop feed mechanism in which the rotary actuator 44 takes the form of a feed eccentric for imparting feed advance and return movements by way of a feed advance rock shaft 47 journaled in the bed, and the rotary actuator 45 takes the form of a gear for imparting movement to a feed lift driving shaft 48 journaled in the bed. Any' conventional work feeding mechanism, however, may be employed.

For driving the loop takers 20, the main shaft 40 extends into a gear compartment 50 in the bed wherein a bevel gear 51 is secured thereto. Meshing with the bevel gear 51 is a bevel gear 52 which is fast on a stud shaft 53 journaled vertically in the bed compartment 50. As shown in FIG. 3, the stud shaft 53 beneath the gear 52 and below the compartment 50 in the bed has secured thereon an enlarged flange 54 of which the periphery is tapered to define a truncated shape 55. Beneath the enlarged flange 54 the stud shaft is provided with a threaded portion 56. A sprocket wheel 57 is carried on the stud shaft 53 and the sprocket wheel 57 is formed with a conical shaped counterbore 58 complemental to the truncated periphery 55 of the flange 54 on the stud shaft 53. The sprocket wheel 57 is secured on the stud shaft 53 by lock nuts 59 and spring washers 60 which provide together with the complemental conical surfaces 55 and 58 for a slip clutch connection between the sprocket 57 and the stud shaft 53 regulatable by the lock nuts 59. This arrangement also provides for a line adjustment of the angular position of the sprocket wheel relatively to the'shaft 53.

The driven sprockets 28 and 28' for each of the loop takers are driven synchronously from the drive sprocket wheel 57 by a single timing belt 70. The timing belt 70 is directed to the driven sprocket wheels 28 and 28' by a pair of idler rollers 71 and 72 so that a separate belt loop 73 and 74 is directed to each of the driven sprocket wheels with each of the belt loops having substantially identical angle of wrap about the sprocket wheels and identical direction of belt travel relatively to the driven sprockets. The aforementioned identical disposition of the belt loops 73 and 74 to each of the driven sprockets 28 and 28' respectively is obtained as viewed in FIG. 4 by an arrangement of the idler roller 72 on a bracket 75 which is secured by fastening screws 76 to the machine frame at a point between the driving sprocket 57 and driven sprockets 28 and 28. The loop 74 of the belt 70, which is directed to the sprocket 28, extends as shown in FIG. 4 from the sprocket 28 toward the right, with an angle of wrap of the belt slightly in excess of 180 of wrap and with that limb of the belt loop which extend to the top of the driving sprocket 57 as viewed in FIG. 4 also extending directly to the top of the driven sprocket 28. The fastening screws 76 for the idler pulley bracket 75 preferably pass through slots 77 in the bracket 75 so that the idler pulley 72 may be adjusted to regulate the slack in the belt 70. The idler pulley 71 is preferably journaled in a bracket 80 which is secured by screws 81 to the loop taker saddle 21 as illustrated in FIG. 4. The idler roller 71 causes the belt loop 73 of the belt 70 to be directed to the idler pulley 28 with an angle of wrap slightly in excess of 180 and with that limb of the belt loop which extends from the top of the driven sprocket 28 being the same limb of the belt which also is directed eventually to the top of the driving sprocket 57.

With this arrangement of the driving belt 70, rotation of the driving sprocket 57 will cause the driven sprockets 28 and 28 to turn synchronously and in the same direction as is indicated by the arrows in FIG. 5. FIG. indicated diagrammatically two extreme positions of adjustment of the loop taker saddles into a minimum and a maximum spacing. As indicated in FIG. 5, the saddles are preferably adjusted equidistant from a medial plane shown by the line X-X in FIG. 5. In making the adjustment of the saddles from that indicated at the top portion of FIG. 5 in the minimum spacing to that indicated in the bottom portion of FIG. 5 in the maximum spacing, the hook saddle 2 l for the right-hand loop taker nearest the drive sprocket 57 would first be loosened by unscrewing the clamp 37 This loop taker saddle would then be shifted to the right as shown in the lower portion of FIG. "5 and the belt 70 would be slackened by an amount very closely approximating twice the dimension which the loop taker saddle is shifted. Preferably, a shift of the loop taker saddle would be made using a gauge block so that when the saddle was again secured in position the loop taker would be very accurately located. When the right-hand loop taker saddle, as viewed in FIG. 5, has been relocated and secured in its new position the left-hand loop taker saddle would then be adjusted by loosening the clamp screw 37 by which the left-hand loop taker saddle 21 is secured in the bed and shifting the saddle to the left as viewed in FIG. 5. Here also the use of a gauge block for setting the new position of the loop taker is preferable and in shifting to the left the left-hand loop taker will tighten the timing belt by an amount which is identical with the amount which the belt will slacken by the adjustment of the right-hand loop taker. When the adjustment of both loop takers had been completed, therefore, the drive belt will again be stretched to the desired tautness. The timed relation of each of the loop takers 20 with respect to the needle 16 with which it cooperates will, however, be disturbed by the change of loop taker position for a changed needle spacing. When the needle spacing is changed in equal amounts on opposite sides of a needle plane XX, however, each of the loop takers will be shifted to the same angular extent and in the same direction out of proper timed relation with its respective needle. In the top portion of FIG. 5 in which the loop takers are illustrated in minimum spacing, the points marked A on each of the sprocket wheels 23 and 28 indicate two given positions of these sprockets. In the lower portion of FIG. 5 the points B indicate the new position of points A after the saddle has been shifted into maximum spacing. As shown by the points A and B in FIG. 5, the drive sprockets 28 and 28 will have shifted the same angular extent, and in the same direction and since the loop takers bear equal relation to the sprockets 28 and 28, the loop takers 20 may be simultaneously brought back into proper timed relation with its respective needle by a single adjustment of the position of the drive sprocket 57 relatively to the stud shaft 53 on which it is carried. This readjustment may be affected by loosening the clamp nuts 59 and turning the driving sprocket 57 into the desired new position after which the driving sprocket may again be secured on its shaft 53 by tightening the nuts 59. The frictional coupling between the drive sprocket 57 and the shaft 53 also provides for a safety feature in that this connection can slip in the event that one of the loop takers becomes jammed so that damage to the expensive loop taker may be forestalled.

Having thus set forth the nature of this invention, what is claimed herein is:

l. A drive mechanism for a pair of substantially parallel axis rotary loop takers in a sewing machine in which each loop taker cooperates with a separate needle, and in which the cooperating sets of needles and loop takers may be shifted selectively to varying positions longitudinally of the sewing machine and equally spaced on opposite sides of a medial plane, said drive mechanism comprising a driven sprocket associated with each of said loop takers, a driving sprocket carried in said sewing machine, said driven and driving sprockets being supported on substantially parallel axes, a single continuous timing belt arranged in mesh with said driven and driving sprockets, and idler pulleys engaging said timing belt and arranged to direct separate loops of said timing belt one to each of said driven sprockets with said separate timing belt loops being substantially identical in angle of wrap about said driven sprockets and identical in direction of belt travel relatively to said driven sprockets in response to rotation of said driving sprocket.

2. A drive mechanism for a pair of rotary loop takers as set forth in claim 1 in which said driven sprockets are each associated with one of said rotary loop takers in a loop taker supporting saddle and said saddles are supported for adjustment longitudinally of the sewing machine, and in which at least one of said idler pulleys is supported on said sewing machine remote from said saddles so that adjustment of the position of one of said loop taker saddles away from the medial plane of said needles will slacken said timing belt and adjustment of the position of the other loop taker saddle away from said medial plane will tighten said timing belt by an equal amount.

may be loosened for repositioning said driving sprocket on said shaft simultaneously to retime both loop takers relatively to their respective needles after a lateral adjustment of the loop taker saddles. 

1. A drive mechanism for a pair of substantially parallel axis rotary loop takers in a sewing machine in which each loop taker cooperates with a separate needle, and in which the cooperating sets of needles and loop takers may be shifted selectively to varying positions longitudinally of the sewing machine and equally spaced on opposite sides of a medial plane, said drive mechanism comprising a driven sprocket associated with each of said loop takers, a driving sprocket carried in said sewing machine, said driven and driving sprockets being supported on substantially parallel axes, a single continuous timing belt arranged in mesh with said driven and driving sprockets, and idler pulleys engaging said timing belt and arranged to direct separate loops of said timing belt one to each of said driven sprockets with said separate timing belt loops being substantially identical in angle of wrap about said driven sprockets and identical in direction of belt travel relatively to said driven sprockets in response to rotation of said driving sprocket.
 2. A drive mechanism for a pair of rotary loop takers as set forth in claim 1 in which said driven sprockets are each associated with one of said rotary loop takers in a loop taker supporting saddle and said saddles are supported for adjustment longitudinally of the sewing machine, and in which at least one of said idler pulleys is supported on said sewing machine remote from said saddles so that adjustment of the position of one of said loop taker saddles away from the medial plane of said needles will slacken said timing belt and adjustment of the position of the other loop taker saddle away from said medial plane will tighten said timing belt by an equal amount.
 3. A drive mechanism for a pair of rotary loop takers as set forth in claim 2 in which said driving sprocket is carried on a shaft operatively connected with the operating mechanism of the sewing machine, and an adjustable slip clutch is provided between said shaft and said driving sprocket which slip clutch may be loosened for repositioning said driving sprocket on said shaft simultaneously to retime both loop takers relatively to their respective needles after a lateral adjustment of the loop taker saddles. 